The 7-21×40 Reverse Porro Gladiator Zoom Binoculars combine extended magnification in a more compact design for greater mobility. The Reverse Porro Prism design creates a more compact over-all size compared to traditional porro prism binoculars, but maintaining full-size features such as the large 40mm objective lenses. The zoom lever allows you to seamlessly transition through the magnification range from 7x for quickly scanning large open areas, all the way to 21x to get a closer more detailed look at your object of interest. The oversized Center Focus Knob is ergonomically positioned for fast and easy focusing while maintaining a natural and comfortable hold. Fully Coated Lenses on all air-to-glass surfaces increase light transmission for a bright, crisp image. The Rubber Armor Exterior provides an added layer of protection, with a textured surface for a non-slip grip. Fold-down Rubber Eyecups are incorporated into each eyepiece providing a comfortable viewing experience with or without eyeglasses. Included with these binoculars are lens covers, a neck strap, and a nylon case for convenient and secure transport. Backed by Barska’s Limited Lifetime Warranty.